2-bis(5-cyclylpyrrole) azamethine dyes



Patented May 10, 1949 2,469,830 2 :-BIS:( 5eGYCIrYIJBYRROLEJAZAMETLHINEA DYES" Edward B'owes Knotty Harrow, Wealdstone, England}. assi'gmm: to Eastmam Kodakr Cbmpanyg. EoohestenNiif;,raicorporationmildew-Jersey.

No Drawing. Application Mam-1'7,"194'7jSlerial'No; 748,839. In Great Britain May 31; 19.46

19 Claims. (CLZZGBm-ZHQQ This invention relates to;. 2-bis(5"-oyolylpynrolelazamethinedyes and toa process for preparing thesame.

2 bis(3:5 diphenylpyrrole.)'azamethine dyes (also called" 2:2z4'z4' tetraphenylazadipyrromethines) have been described in Uni-ted States Patent No.- 233825914; dated August 1E 9453 These lnown I dyes can. be represented-bythe foll lowinggeneraliformulas" 1: Ar Ar wherein.Ar represents atphenyl group whichimaw be substituted withvchlbrine, methyl, dimethylamino, nitro, etc. These known dyes are prepared by the interaction of p-aroyl-e-arylpropianitriles with an agent whichyields ammonia,.,e. g. fbrmamide urea, ammonium: formate, ammonium phosphate and ammonium carbamate";

I have now found that the aforesaid known 2'-bis (3": 5"- diarylpyrrole)jazamethine, dyes" can; he.

prepared" by the interaction offfii-aroyla-aryll propionitriles with hydroxyl'aminesal't's'z. More over;v Ii have-e foundi that fieoyoihylpropionitrllesg, in general, reacttwitnmydi'onylaminewsalts to give 2-bis(5-cyolyl-pyrrolelazamethine. dyes... whether a or, not the.B-QYclbylpropiOnittile:contains anialiyl. group. in thearposition, so that. by my, newpmcesa many. new. dyes aremadeavailable.

It is. ,accordin lisan .obj ect-.of-. my inventiomtot provide; a process. for preparing; 21bisi5-cyclyl=-- nyrrole) azamethinedyesi A further, objeet iato; provide new dyes. Other objects will become apparent hereinafter.

In. accordance with myinvention; I prepare. 2-bis(5-cyclylpyrrolelazamethine dyes which can be represented by. the following general formula:

whereinrRtrepresentsatcyolylsgroiimer .g.-',a -monoe oyolimarylxgroumof: theabenzenes series-,: espeoially-; such: a1. group; having an. atomic weighttfmmithes atomic weightzofmherphenyjl groumto; thezatomic: weight: of: the:- p-eiodonhenyl group, ion instaneea, the=;phenyl&gronp;,th62p-tolyllgmlm. the xm-tolyh group, the-.1 nenitmnhenyb group;, the; premier};

- Formula II in" which R represents a: hydrogen atomiare new: d'yes whielb were heretofore' -unavailable; Tli'ese new dyes: are-mueh more basicthem theaforesaid lsinown divesand the-salts of themevedyes are more" stable thanthe: salts-of I prepare. the azamethine dyes represented by Formula II above by heatin a' ,fl -cycleylpropio nitrile selected from those represented 'by: the fbilowihg'general formula:

In: R

CHQT-(EH R-.';O. en. wherein R and-.31 have. the, values. given above and RC. can; in addition, represent a carboxyl group, with ahydroxylaminesale; e. g, hydroxylamine chloride, hydroxylaminevnitrate, hydroxylamine sulfate, etc.

In my new process, the dyes are sometimesob- 4 tained in their ammonium salt": form which-- can.

hemepresented' by thefollowing "general'fformula:

wherein R and R. harvest he values given above,

* and X represents an acid group, i. e. an anion,

erg: air anion-theatomiet'weight'"ofwhichi' is from. the atomic weight of the chloride anion" to'the" atomie'r weight of the-iodide; anion,- forinstance; the chloride aniorr, thebromideanion, the nitrate anion, the hydrosulfate anion, tiie'a'cetate anion,

the: iodideeaniom, etc: These ammoniumi-saiti" forms wherezRfi' represents amarylrgroup hydrolyze rapidly even in ordinary, atmospheres to give. the free basejorm of the dyes shown .in.Formula.

' II above. The aanmonium-salt forms of a11= the dyes can be converted'to the free base forms bytreating the ammonium salt forms with aqueous:

alkalies, e. g. sodium or potassium hydroxide.

The-a2amethine=salts obtained byvmymew'proc- 55E essihaveamelting.rpointseini-eXceSS oJfi'SBO CZ 'I he 3 free bases can be quaternarized (i. e. converted to quaternary ammonium salt forms) by heating with alkyl salts, e. g. methyl iodide, ethyl iodide, methyl p-toluenesulfonate, methyl benzenesulfonate, n-propyl bromide, n-buty1 chloride, isobutyl iodide, diethyl sulfate, etc.

Advantageously, in my process, the heating is efiected in ethyl alcohol or in aqueous ethyl alcohol or in water or in any other solvent which dissolves both reactants, i. e. the nitrile and the salt. The heating is advantageously done at from about 60 to about 150 (2., although other temperatures can be employed.

When R in the above Formula III for the original fl-cycloylpropi-onitrile is a carb-oxyl group, carbon dioxide is lost during the reaction to yield a dye in which R is a hydrogen atom. The hydroxylamine salt is advantageously employed in excess; for example one molecular proportion of nitrile and 4 molecular proportions of hydroxylamine salt will give a yield of dye as high as 90 per cent in some cases. It has been found that in the case where R in the above formula for the original fi-cycloylpropionitrile is phenyl, somewhat higher temperatures of heating are advantageously employed, for example approximately 120 C. The new azamethine dyes can be sulfonated if desired.

The azamethine dyes are very stable blue dyes or pigments which are valuable for coloring layers in sensitive and non-sensitive photographic materials. For example, the dyes can be dispersed in layers of gelatin or of synthetic resins, such as polyvinyl phthalate, the pH being preferably adjusted to less than 3 in gelatin and less than '7 in polyvinyl phthalate. The dyes also find application in color photography in the imbibition process.

The preparation of dyes by my new process will be further illustrated by the following eX- amples:

Example 1, 2-bis(5-phenylpyrrole)azamethine dihydrochlorz'de HC=CH Example 3. Z-bis(5-p-methoxyphenylpyrrole) aeamethine dihydrochloride Etc-H HO=CH I CHaO H H t droxylamine hydrochloride (5.6 g.) and industrial fi-p-Methoxyphenylpropionitrile (6.75 g.), hy-

4 spirit (ethyl alcohol) (29 cc.) were refluxed for 2 hours. The dye which precipitated was filtered off and washed with acetone. The dye was in the form of coppery crystals which can be recrystallized from pyridine.

Example 4. 2 bis(5-p-hydrozryphenylpyrrole) azamethine dihydrochloride p-p-Hydroxybenzoylpropionitrile (17.5 g.), hydroxylamine hydrochloride (14 g.) and spirit (ethyl alcohol) (100 cc.) were refluxed for 2 hours. The crystals which formed were collected, washed with acetone and dried. The crystals were green in color and gave a green solution in aqueous sodium hydroxide and a blue solution in organic solvents, e. g. in methyl alcohol or acetone.

Example 5. 2 bis (5 1-naphthylpyrrole)azamethine dihydrochloride Ho=ori fl-l-naphthoylpropionitrile (2.09 g.) hydroxylamine hydrochloride (2.8 g.) and spirit (ethyl alcohol) I cc.) were refluxed for 1 hour. The dye which formed was collected and washed with acetone. It was in the form of a bronze, crystalline powder. It can be recrystallized from acetic acid or from pyridine.

Example 6.-2 -bz's( 5 -z-thienylpyrrole) azamethine dihydrochloride Example 7.-2-bz's(5 4 methylphenylpyrrole) azamethz'ne dihyclrochlo ide ,6-4-methylbenzoylpropionitrile (8.65 g.), hydroxylamine hydrochloride (14.9 g.) and spirit (ethyl alcohol) cc.) were refluxed for one hour. The dye which formed was collected when the reaction mixture was cold. The dye was Washed with acetone, water and again with acetone. It was in the form of a bronze crystalline powder.

i? EC 2C1- Escample 8. 2 bis(5-phenyZpyrroZe) azamethz'ne "rnonohg/drochloride B -o1-1 HC- CH Q ea -Q t v j H H fl-Benzoylpropionitrile (1.59 g.) hydroxylamine hydrochloride (1.4 g.) and water 20 cc.) were refluxed for 2 hours. Acetone (20 cc.) was added to the cool reaction mixture and the free base which precipitated was collected. Recrystallized from n-butanol it formed tiny pointed needles, M. P. 242 C. This same free base was obtained by treating the azamethine dihydrochloride of EX- ample 1 with aqueous sodium hydroxide.

Example-- 9.-' 2*- li2's=(5 -piienyljtyrrol) azame'flz'ine' dihydroohlorzde fi-Benzoylpropionitrile (4:7?7. g.) ,hydroxylamine. hydrochloride (2.1 g.) and nebutyl alcohol (10 cc.) were refluxed for 45 minutes by which time. the whole .had solidified. The dye was broken up under acetone, collected and washed with acetone.

Example-=1 Z.-2 f-bis (.i-m methoxyphenylpyrroZe) aza'methinetdihydrochlorid'e p3-m-Methoxybenzoylpropionitrile' (3.8: g.) hydroxylamine hydrochloride (5.6- g.) and industrial spirit (ethyl alcohol) (205cc) were refluxed for 2 hours. After chilling the reaction mixture, the dye was collected, washed with methanol and acetone, and recrystallized from acetic acid whereupon it was obtained' asbronze-needles.

Example 11 .-.2-bis,(5;phenylpyrrole) azamethine dihydrochlorz'de m-Gyano-flbenzoylpropionic. acid; (arcarboxy- ,B+benzoylpropioni trile)2 (223. g.),,. hydroxylaminehydrochloride 1. (141g) 1 and. industrial .spirit (ethyl; alcohol) (100. cc.) werezrefluxed for 90 minutes by: which. time the: dye had: crystallized. out. It was collected, washed with; a littlexspirit. (ethyl; alcohol), then" acetone. and dried.. It. was recrystallized: from; pyridineand obtained as... purple needles.

Example 121-2 bis(3' 5 diphenylpyrrole) azamethine'.

(a) c-Benzoyl-u-phenylpropionitrile (4.7 g.; 0.02 mol.), hydroxylamine hydrochloride (1.4 g.; 0.02 mol.) and ethylene glycol (20 cc.) were heated'at 120C. inian' oil bath for 2h0urs'. The dye separated as coppery crystals. These were collected'when the reaction mixture was cold'and' recrystallized'from nitrobenzene whereupon the; dye was obtained as short needles, melting at 286C:

(1),) Proceeding as in (a): above, but using nbutyl. alcohol (20 cc.) as. the solvent instead of ethylene glycol; and refluxing for 2' hours, the deep blue solution deposited 2-bis(3:5-diphenylpyrrole)azamethi'ne dihydrochl'oride upon chilling. The purple solid rapidly acquired a coppery sheen on standing in the atmosphere owing to hydrolysis of the dihydrochloride to the free base (M. P. 286 C.)

(c) fl Benzoyl-a-phenylpropionitrile (4:7" g.), hydroxylaminehydrochloride (IA-g.) and form-- amide (20 'cc.) were placed in an oil bath-at 120 C. The temperature of the'reaction'mixture'rose to 90" 'C., then with evolutionof gas; the'temperature rose to 150 C. and the dye separatedout. It" wascollecte'd' after'diluting the reaction mixture with ethyl alcohol, ground with ethylalcohol and then washed with ethyl alcohol-and-water. It had M. P. of 286 C. and was identical with the dye prepared according to (a).

a-Carboxy-p-benzoylpropionitrile can be prepared from the corresponding [i-aroylacrylic acid by treatment" with' an alkali cyanide (see Bougault, .chim. phys, 1'5;504 ('1908)):. The

6.. c-aroyl acrylie' acid can be prepared-by known methods, for" example froman aromatie hydrocarbon, maleic anhydride andaluminium chloride, or from" a ,8 -bromo-fi-a-roylpropionic acid and an alkali-salt, such as'sodium'aoet'ate:

fl-Benzoyl-propionitrile can. be prepared from phenyl vinyl" ketone and hydrogencyanide-.- Allenet al.', J; Org: Cher-11., 2; 227 (1937)-.

I have found a simple method for" preparing ,c-cycloylpropionitriles which comprises heating a c' dialk-ylamino ethyl cycl'yl" Ketone -salt selected from those represented by the following general formula:

V. Ri

R;o O.GHi CHz .N 11x1 wherein R represents the'value given" above, ire: a; cyclylgroup, e; g; phenyl; naphthyl; Z thienyI'; 2.-furyl; 2-thiazolyl, carbazyl; tetralinyl, etcz', Rir represents an' alkyl-"group, e': g. methyl, ethyl, 11- propyl, n-butyl; isobutyl, etc and Xi represents an anion, e. g. chloride; hydrosulfate; bromide; iodide, etc;, with a metal cyanide: The metal cyanide is. advantageously watersoluble; e: g; an alkali metal cyanide; for" instance sodium" or. potassium cyanide.

The course of the reaction can be illustrated for a specific embodiment asfollowse CsHy-C O-CHg,GH-2.-N(CH;)g-HG1.+ KoN on. CIGHK-GCH2- CHT-N{CHZ)I2LH K01 GaH5C O--CHr-CH2-CN (OHMNH The dialkylamine liberated during" the 'reaction can be recovered by steam. distillation and absorption in dilute hydrochloric acid;

The most suitable reaction time,.. temperature and dilution of the reactantswill vary somewhat, depending upon the particular ;8'-diall ylamino ethyl cyclyl ketone salt employed: Generally speaking the cleanestprod'ucts andhighestyields; of nitrile are obtained when the metalcyanideis employed in, excess of'the'theoretically required amount and at a dilution. of not greaterthanfi" per cent. The reaction time willivary between 5 and 60 minutes, although'20 minutes" at 100" C! gives about the best yields, inmost cases:

In most cases, the nitrile crystallizes, onco'olingthe reaction mixture, but in the case whereiR represents Z-furyl, the nitrile, must be extracted from the aqueous reaction mixture" by a water immiscible solvent, such as-chloroform, etheror' benzene. The yield of'nitrile' variesbetweerr 30 and per cent depending'on the nature ofthe starting: cediallcylaminoethyl. cyclyl, ketone; salt.

The nitriles are readily hydrolyzed to c-cycloylpropionic acids on: refluxing the nitrile with aqueous hydrochloric acid, e g. with equal volumes ofwater and concentrated hydrochloric acid (sp..g. 1.18) Inthiszway- ,B-cycloylpropionic acids are: made; readily available. which. cannot. be preparedby the:v normal method, e..g. 3,-2.1- furoylpropionic acid is,-readily prepared aswell. as substituted. fir-benzoylpropionic acids in which. the substituents are. not. situated inthepara post-- 131011;

The following, examples will. servetoillustrate: furtherithe-preparation of fiecycloylpropionitriles...

Example 1 3'.-fl -BenzoyZpropionittiZe (a) 13 Dimethylaminopropiophenone hydro chloride (213.5 g.; 1' mol.), potassium cyanide (71.5 g.; 1.1 mol.) and water (1400 cc.) were refluxed for 60 minutes. The fi-benzoylpropionitrile separated as an oil which crystallized upon cooling and a further quantity crystallized from the liquor. Recrystallized from benzene-light petroleum, the fi-benzoylpropionitrile formed almost colorless blades M. P. 76 C. Yield 67 per cent.

(1)) Crude l3-diethylaminopropiophenone hydrochloride was prepared by refluxing for 2 hours acetophenone (1 g.; 1 mol.), paraformaldehyde (1.3 g.; 1 mol.) diethylamine hydrochloride (1.35 g.; 1 mol.) concentrated hydrochloric acid (2 cc.) and ethyl alcohol (160 cc.) and then precipitating the total salts with anhydrous diethyl ether. Yield 901 g. from 500 g. of diethylarnine hydrochloride. The crude salt (24.1 g.), potassium cyanide (13.0 g.) and boiling water (520 cc.) were refluxed for 20 minutes. The nitrile obtained after one recrystallization from benzene-light petroleum represented a 48 per cent yield based on the diethylamine hydrochloride.

(c) The aforesaid crude salt (24.1 g.), potassium cyanide (13 g.) and boiling water (260 cc.) refluxed for minutes gave a 43% yield of nitrile based on diethylaznine hydrochloride.

((1) Same as in (0) but refluxed for 30 minutes gave a 46 per cent yield of the nitrile.

(e) The aforesaid crude salt (24.1 g.), potassium cyanide (7.1 g.) and boiling water (100 cc.) gave after refluxing for 45 minutes a 45 per cent yield. The hydrolysis of this nitrile to the corresponding acid has been described by Allen et al.

(100. cit.).

Example 14. 64-methoxybenzoylpropionitrile 8- Dimethylamino p methoxypropiophenone hydrochloride (24.35 g.) obtained from p-methoxyacetophenone, paraformaldehyde and dimethylamine hydrochloride by the method of Mannich and Lamrnering (Ber., 55, 3510 (1922)) in 86 per cent yield, potassium cyanide (13 g.) and boiling water (520 cc.) were refluxed for minutes. Gn cooling the nitrile crystallized. It was recrystallized from ethyl alcohol and obtained as colorless needles, M. P. 95 C., in 71 per cent yield.

This nitrile (2 g.) was refluxed for 60 minutes with concentrated hydrochloric acid (10 cc.) and water (10 00.). The oil solidified during this process. Upon recrystallizing the oil from hot water, colorless needles of fil-rnethoxybenzcylpropionic acid, M. P. 144 C., were obtained.

Example 15.p-4-hydroxybenzoylpropionitrile ,B-Hydroxyacetophenone g.), paraformaldehyde (7.2 g.), dimethylarnine hydrochloride (20 g.), concentrated hydrochloric acid (0.75 cc.) and ethyl alcohol (99 per cent) cc.) were refluxed for minutes. After 10 minutes the whole had almost completely solidified. The solid was collected and recrystallized from ethyl alcohol forming glistening plates of fi-dimethylamino-phydroxypropiophenone hydrochloride, M. P. 198 C., in 76 per cent yield. The hydrochloride (22.95 g.; 0.1 mol.), potassium cyanide (13 g.; 0.2 mol.) and boiling water (520 cc.) were refluxed for 30 minutes. The clear, yellow solution was cooled and. acidified in the fume cupboard. The required nitrile was thus precipitated as glistening, colorless crystals. From ethyl alcohol it formed flat needles, M. P. 162 C. with previous softening, in 59 per cent yield.

This nitrile (2 g.) was refluxed with hydrochloric acid and water as in Example 14. The p-hydroxybenzoylpropionic acid, however, was water soluble and crystallized only on cooling. From hot water it formed almost colorless needles, M. P. 157 C. in per cent yield.

Example 16.B-2-furoylpr0pionitrile e-Dimethylaminoethyl 2-furyl ketone hydrochloride (81.4 g.) prepared according to the instructions of Levy and Nisbet (J. Chem. Soc. 1938, 1055), potassium cyanide (57 g.) and boiling water (2850 cc.) were refluxed for 20 minutes, cooled rapidly and the clear, orange liquor eX- tracted repeatedly with chloroform. The dried chloroform extract was evaporated, leaving a brown oil which solidified completely. From ethyl alcohol, the nitrile formed almost colorless needles, M. F. 74-76 C.

This nitrile (2 g.) was refluxed for 60 minutes with concentrated hydrochloric acid (10 cc.) and water (10 00.). The reaction mixture was then evaporated to dryness. The crystalline solid was recrystallized from hot water and formed shiny, flat, fawn needles, M. P. 119 C. with previous softening, of ,8-2-furoylpropionic acid, in 95 per cent yield.

What I claim as my invention and desire to be secured by Letters Patent of the United States is:

1. An azamethine dye selected from the group consisting of those represented by the following general formula:

HC-CH :011 at in.)

wherein R represents a member selected from the group consisting of a monocylic aryl group of the benzene series, an aryl group of the naphthalene series, a Z-thienyl group, a 2-furyl group, a 2- thiazolyl group, a carbazyl group and a tetralinyl group, and the ammonium and quaternary ammonium salt forms of said dye.

2. An azamethine dye selected from the group consisting of those represented by the following general formua:

wherein R represents a monocyclic aryl group of the benzene series the atomic Weight of which is from the atomic weight of the phenyl group to the atomic weight or the p-iodophenyl group, and the ammonium and quaternary ammonium salt forms of said dye.

3. An azamethine dye selected from the group consisting of those represented by the following general formula:

l N N l wherein It represents a naphthyl group.

5. The azamethine dye which is represented by the following formula:

6. The azamethine dye which is represented by the following formula:

c- --cn Razor:

'7. A process for preparing an azamethine dye which comprises heating a hydroxylamine salt with a B-cycloylpropionitrile selected from those represented by the following general formula I RCO CN wherein R represents a member selected from the group consisting of a monocyclic aryl group of the benzene series, an aryl group of the naphthalene series, a 2-thienyl group, a 2-furyl group, a 2-thiazolyl group, a carbazyl group and a. tetralinyl group, and R represents a member selected from the group consisting of a hydrogen atom, an alkyl group containing from 1 to 4 carbon atoms, a monocyclic aryl group of the benzene series, an aryl group of the naphthalene series and a carboxyl group.

8. A process for preparing an azamethine dye which comprises heating a hydroxlylamine salt with a fi-cycloylpropionitrile selected from those represented by the following general formula:

RCO ON wherein R represents a monocyclic aryl group of the benzene series the atomic weight of which is from the atomic weight of the phenyl group to the atomic weight of the p-iodophenyl group.

10. A process for preparing an azamethine dye which comprises heating at from 60 to 150 C. hydroxylamine hydrochloride with a fl-cycloyl propionitrile selected from those represented by the following general formula:

CHr-CH:

Rte N wherein R represents a monocyclic aryl group of 10 the benzene series the atomic weight of which is from the atomic weight of the phenyl group to the atomic weight of the p-iodophenyl group. 11. A process for preparing an azamethine dye which comprises heating at from 60 to C. in a solvent for the reactants, hydroxylamine hydrochloride with a fl-cycloylpropionitrile selected from those represented by the following general formula:

CHg-CH:

ROCN

wherein R represents a monocyclic aryl group of the benzene series the atomic weight of which is from the atomic weight of the phenyl group to the atomic weight of the p-iodophenyl group.

12. A process for preparing an azamethine dye which comprises heating a hydroxylamine salt with a B-cycloylpropionitrile selected from those represented by the following general formula:

CH2CH: R310 0N wherein R represents a naphthyl group.

13. A process for preparing an azamethine dye which comprises heating hydroxylamine hydrochloride with a fi-cycloylpropionitrile selected from those represented by the following general formula:

om-om ROCN wherein R represents a naphthyl group.

14. A process for preparing an azamethine dye which comprises heating, at from 60 to 150 C., hydrcxylamine hydrochloride with a p-cycloylpropionitrile selected from those represented by the following general formula:

GHQ-CH2 R 0 ON wherein R represents a naphthyl group.

15. A process for preparing an azamethine dye which comprises heating, at from 60 to 150 C. in a solvent for the reactants, hydroxylamine hydrochloride with a fl-cycloylpropionitrile selected from those represented by the following general formula:

No references cited. 

